I just thought I'd move this post over here from HWC because I've been looking around for replacements and remembered how important this mod was for anybody with PC350's.
The original Hero Mod post from Head-Fi can be found here.
Now, I didn't really even think of taking pictures until someone (Dalton?) in IRC mentioned it, so this is a little bit in. All my tools and whatnot, I didn't use the Dremel however. I've already removed the ear pads and the screws for the right side at this point. The pads just pop off, but take quite a bit of force.
Close up of the right ear's insides.
Here's what I used to make the holes, pretty simple stuff. Heat the nail up with my butane torch and shove it through. Beats the chance of drilling it and having plastic shards stuck inside the driver. (Nail is post-mod, 2mm in diameter)
First hole done. Went pretty easily through, until the head of the nail burned my thumb through the glove I was wearing.
And here's what I'm guessing is the equivalent of a "Warranty void if removed" sticker. Oh well, just jabbed the screwdriver through it.
And here is where the problem happened. Tried doing the left side and ended up having the nail cool down way quicker than the right side. Yeah, it was stuck pretty damn good. Just torched the part of the nail sticking out and yanked it. Either way it ended up pretty good. I had to go and do it a second time because the bass was noticeably heavier in the right ear. You just have to make sure they're both about the same size and in the same position.
And in the end I now have a headset with a nice punchy bass and clearer lows, instead of sounding like tin cans. Many people did 3+ holes, but the one hole seems to do quite a bit while not making it cause problems (Some people reported the bass lasting too long, for example).